Darstellung und Kristallstrukturen von LiGaBr4 und LiGaBr3/Preparation and Crystal Structure of LiGaBr4 and LiGaBr3

Abstract

The com pounds LiGaBr₄ and LiGaBr₃ are prepared by reaction of stoichiometric mixtures of LiBr and GaBr₃ or GaBr₂, respectively, in glass am poules at 250 °C. Single crystal X-ray studies show LiGaBr₄ to be isotypic to LiAlCl₄ containing GaBr₄ tetrahedra arranged as in the structure of SnBr₄ and Li⁺ ions filling octahedral voids [d̄(GaBr) = 232.5, d̄(Li -Br) = 280.3 pm]. LiGaBr, has to be formulated as Li₂[Ga₂Br₆] and the Ga -Ga-bonded unit Ga₂Br₆ has an ecliptic confor­mation. The L i⁺ ions occupy octahedral voids, and the LiBr₆ octahedra are linked via apices, [d(Ga -Ga) = 240.4, d̄(Ga -Br) = 238.9, d̄(L i-B r) = 281.1 pm]. The structures is compared with the structures of PuBr₃, Re₃B, FeB and Ga₂I₃, and the group-subgroup relationship with GdFeO₃ is established.